1. Field of the Invention
The present invention relates to a light-source driving device, an optical scanning device, and an image forming apparatus. More particularly, the present invention relates to a light-source driving device that drives a plurality of light-emitting units, an optical scanning device including the light-source driving device, and an image forming apparatus provided with the optical scanning device.
2. Description of the Related Art
In image forming apparatuses such as laser printers and digital copiers, there has been an increasing demand for improving image forming speed (speeding up) and writing density (higher image quality). As one of methods for responding to this demand, a method of using a multibeam light source capable of emitting a plurality of light fluxes to scan a surface to be scanned with the plurality of light fluxes has been considered.
Incidentally, in the multibeam light source having a plurality of light emitting units, in order to narrow an interval between scan lines, the light emitting units are mutually shifted from each other with respect to a direction corresponding to a main scanning direction. In this configuration, to align write start positions in a plurality of scan lines, it is necessary to control a turn-on timing of each of the light-emitting units.
For example, Japanese Patent Application Laid-open No. 2003-276234 discloses an image forming apparatus that includes a control unit. This control unit controls turn-on of a plurality of light-emitting units in a light source unit by determining a turn-on timing of at least one of the light-emitting units in the light source unit based on an image clock generated in synchronization with a detection signal of a synchronous detection unit, and determines turn-on timings of the other light-emitting units by changing a count value of the image clock.